Computer Configuration > Administrative Templates > Google Chrome
Both
HKLM\Software\Policies\Google\Chrome
Encrypted ClientHello (ECH) is an extension to TLS to encrypt sensitive fields of the ClientHello and improve privacy. If this policy is not configured, or is set to enabled, Google Chrome will follow the default rollout process for ECH. If it is disabled, Google Chrome will not enable ECH. When the feature is enabled, Google Chrome may or may not use ECH depending on server support, availability of the HTTPS DNS record, or rollout status. ECH is an evolving protocol, so Google Chrome's implementation is subject to change. As such, this policy is a temporary measure to control the initial experimental implementation. It will be replaced with final controls as the protocol finalizes.